Polished Dark GUI

Several menus

In order: loom, blast furnace, survival inventory, enchanting table, blast furnace, anvil, grindstone, cartography table, brewing stand

Several menus 2

In order: Horse inventory, Dispenser/dropper, Ender chest, Beacon, Villager trading, shulker box, chest

Several menus 3

In order: Stonecutter, creative inventory, recipe menu, hopper, smoker, smithing

Title screen

Buttons, sliders, widgets are all themed blue, with red as the accent color. The title screen & realms logos are unchanged.

Options

Inventory (survival mode)

The fox is only present with optifine or equivalents (like optiGUI). It's an animation I made to make survival inventory a little cozier

Creative search

Recipe book and creative inventory are similar styles

Furnace

Blast Furnace

.

Anvil

Grindstone

Stonecutter

Smithing

Loom

Beacon

Crafting table

Enchanting table

Horse inventory

Villager Trading

Brewing Stand

Cartography Table

Smoker

Chest

That little cat moves around a bit, since chests are opened so often and it felt empty :)

Ender chest

Shulker box

Hopper

Dispenser / Dropper

HUD

The green-blue gradient is also present in all inventories since it might help identify items